URBAN LEGEND

Wouldn't that mess up the hood paint?

BobSWFL

Let's just say the hood vent is underutilized in the stock configuration. This is a result of the many compromises required of a DOT approved mass production car. This includes noise abatement, water intrusion, fluid escape from a leak, overall drag (cd) which would be impacted if you allow more air to pump through the engine compartment, MPG impact of a higher cd, under hood packaging constraints, etc.

In other words, maximum cooling is not the primary objective of the manufacturer.

The duct is restrictive since it only helps a small portion of the radiator. Radiator efficiency gives diminishing returns with an over-abundance of airflow. So the hood vent is under-utilized and the ducting to it is restrictive. The shroud under the hood vent is restrictive.

The area in front of the engine is cluttered with components, mostly engine intake related. There was only room for a small duct for a small portion of the radiator. This allowed Chevy to proudly claim the following:

"All vents are functional!!" That does not mean they function enough.

The majority of air from the radiator (below the duct) blows directly onto the engine and SC. With my mod some of this hot air will exit via the hood vent.

Problems: Only small areas of the hood are low pressure areas. Exit vents can only work well in these areas. If this first mod is effective, the challenge will be to find which other areas of the hood are also low pressure for further venting.

On the other hand, I might be completely wrong about all of this.

rwheelz

For $40 you can buy a pressure sensor and test anywhere you would like in the engine compartment. It would be incredibly easy to determine whether there is adequate airflow or whether more/larger vents are needed.

JoesC5

While the duct allows approximately 25% of the air flowing through the radiator to vent out the top of the hood, it does not restrict the remaining 75% of the air flow that is passing through the lower 3/4's of the radiator into the engine compartment that exhausts through the fender vents, and under the car. Removing the duct and plugging the hole in the hood would just mean that 100 % of the air passing through the radiator would have to be exhausted through the fender vents and under the car. The radiator cooling fans are located under the duct and they do not move any air through the duct.

FiremanC7

You will also lose downforce! And gain Front end lift.

BobD

jaden61

Exactly.

BobSWFL

Don't plug the vents in the hood! Wow. Why would you plug up the vents?

I believe there is not enough venting from under the hood. The cross section of the current duct is much smaller than the total area of the current, available vents. By removing the ducting we can INCREASE the amount of air venting. This should increase the total amount of air through ALL of the radiator.

BobSWFL

No, you will increase front downforce.

Moving more air through the grill/radiator and venting more air out the top of the hood will increase downforce.

Why in the world are people considering CLOSING the hood vents?

Snorman

Those are fairly easy to remove. I would suggest removing them between sessions at the track and collecting before and after PDR data.
S.

CDNZR

If this does not work, why not mount couple 5" Spal Fans and draw cool fresh air into the engine compartment? I am sure there's enough room for this no?
I am no expert fabricator but I have done such things to my last C4 just for fun and giggles. With this fear of overheating issue, I have no doubt that I will find a way to solve this with some logical/common sense thinking if I had a C7 Z06.
My list would be to combination of larger radiator, oil cooler, eliminate/prevent heat soaking of the intake, add fans for cooler air into the engine compartment, and tuning.

Cyclone09Z06

I will do this this coming weekend, although I have been told it will not do much as the air under the hood evacuates very good.

I believe that there are very smart people working on this

BobSWFL

Excellent. Any results to prove or disprove the venting theory will guide the next step.

We had a similar overheating problem with the 1996 Mustang Cobra on the track. Everyone argued about venting until we started cutting holes in the hood.

By the way, here is the solution Ford eventually offered. It included a less restrictive A/C condenser, a much thicker radiator, and a larger electric fan. Ford gave it to you under warranty if you complained enough:

http://www.ebay.com/itm/FORD-MUSTANG...-/151084493564

Let me repeat: Ford offered a fix after enough people complained!

URBAN LEGEND

Loving the F1 aerodynamisists in here.

SBC_and_a_stick

If only I saw this earlier before I asked Tadge for a cooling pack. This is a tailor made solution from Ford much like what we need. It would have been nice to have it as an example. I did list the Shelby GT350 track pack with the oil cooler as an example so I think that's similar.

descartesfool

LoL

Now all we need are some wool tufts.

SBC_and_a_stick

Not to sound like a jerk, but the only way I see this working is if there is an inherent tradeoff between downforce and cooling. If removing the duct improves both, GM would have done it. It makes no sense to make additional parts to achieve all around less output. They can sell Corvettes with or without a heat shroud. It's all under the hood anyway. It has no marketing purpose.

Lawdogg

Ever seen a world challenge corvette hood? Whole thing is vents. I have one on my modded C6 Z06 and saw oil and coolant temps both fall at the track by about 25 degrees. From what I've read, the hood also creates more front downforce than the ZR1 style splitter. I don't know why venting more of the radiator out the hood wouldn't have the same effect on a C7 Z06.

soulsea

Stage 4 aero with cooling pack:

SBC_and_a_stick

My guess is that ideally you want two things:
1. A heat extractor like the one we have except as large as the radiator face and vented through the hood with a profile optimized on a software program for velocity, pressure, or what have you.
2. Additional vents as needed to draw more heat out.

I think more venting of the hood in addition to the already existing heat extractor would work.

OnPoint

Perhaps Halltech, LG or Katech could whip up a vented World Challenge type hood.